Mold for rubber mats, etc.



, pm L 1923.

n.. M1., mmm'lr'r MOLD FOR RUBBER MATS, ETC

FiledJune 23 1922 www@ Mm mwa auf@ ntentetll r.. 24

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LEROY M. BCKETT, 0F WATERTOWN, WKSCONSN.

MULJD FUR RUBBER. MATS, FTC.

Application led .lune t3, wat.

To (rtf whomfit' may concern.'

lie it known that ll., Lener lill. litrciter'r, a citizen of the llnitedStates., residin at lllatertown, county of Jefferson, and tate ofWisconsin, have invented new and useful improvements in Molds for Rubberllvlats` Fte., of which the following is a specitication.

'l`his invention relates to improvements in molds for rubber mats,sheets, and other articles made from rubber.

lleretofore such molds have been made of rubber in the form of a mat orsheet having a figured upper surface., which was the counterpart of theconhguration desired to be produced on the surface of the article to bemanufactured. These rubber molds sometimes were provided with a baclringof canvas, and were vulcanized to a desired extent. 'llhen by spreadingraw rubber over the upper surface of such a mold and placing the mold ina press, the raw rubber could be forced into conformity with theconfiguration of the mold and simultaneously heated to vulcaniae it tothe desired extent. rlhereupon the press platen could be retracted andthe contoured article removed from the mold and trimmed along itsmargins to the desired sise.

llt has been found7 however, that molds made as above described areprogressively distorted whenever they are subjected to pressure in thepress. @auch distortion sometimes consists merely in expansion. ditother n times, due to the unequal expansion, the

shape and configuration are changed, even the surface configurationdistant from the margin being frequently altered to such an extent as toimpair the attractiveness of the design. For these reasons the moldsheretofore made are serviceable for only a few opcrations, whereuponthey must be discarded and new molds substituteth thereby entailinglarge expense and also causing serious loss by reason of the productionof inferior or second grade mats.

The object of my invention is to provide means whereby a mold of thedescribed type may be made, which will not expand or become distorted bycontinued use, thereby prolonging the life of the mold and enabling themanufacturer to produce mats or other articles of uniform quality andexact and unvarying design and size.

ln the drawings:

Figure 1 is a sectional view of a portion of one of my improved molds.

Figure 2 is a fragmentary plan view.

Figure 3 is a side View showing fragments of the mold separatedvertically from each other to clearly expose the elements composing themold.

Figure 4l is a detail View showing a por tion of the re-enforcingelement or metallic net.

Figure 5 is an elevation showing the working elements of a press as itappears in a mat-forming operation, the mold and the completed mat beingshown in section.

Fi re ti is a fragmentary sectional View showing a portion of acompleted mat as it appears preparatory to its removal from the mold.

Lilie parts are identified by the same reference characters throughoutthe sr 'eral views` lln the manufacture of my improved mold, l firstprepare a foraminous metallic element, such for example as the woven orcrossed wire net l illustrated in Figure ll. ll preferably stiffen thisnet by soldering or welding the wires together at the crossing points,as indicated at 2 in Figure t. lf then taire a sheet 3 of raw rubber(Figure 3) and place this re-enforced or rigid foraminous elementthereon, after which, ll cover it with another sheet of raw or partiallyvulcanized rubber t. lhon by means of a suitable die or pattern plate 5l impress the desired surface configuration in the sheet 4l, thisoperation being preferably done in the press illustrated in Figure 5, inwhich superposed elements are placed between the upper and lower platensor press plates 7 and 8, whereby the pattern plate or die 5 may have itsridges and other projections forced into the material composing theelement l, and said element l may be simultaneously pressed upon theelement 1 with sufficient pressure to cause the rubber in the elements 3and l to pass through the openings in the element l and meet or mingle.Yl`he press platens 'i' and 8 are heated in accordance.

with the practice common in this art, these platens being made hollowfor the admis sion of steam. Therefore, the rubber elements 3 and t ofthe mold are vulcanized during the compressing operation and are (illlili

united to each other with the net 1 embedded therein, i. e., in therubber of the two elements 3 and 4.

If desired, the element 3 may be made very thin, whereby when thepressing or moldforming operation is completed, the element each other,the pattern form 5 may be removed and the mold is then ready for use,either with or without marginal trimming.

The mold may then be used in the ordinary manner for shaping andvulcanizing mats or other articles, in the manufacture of which rawrubber is placed or spread over the upper surface of the mold andcompressed or vulcanized between the press platens 7 and 8.

It has been found in practise that by employing a foraminous element ornet 1, which will not distort or expand under pressure exerted by thepress platens, the mold can be used for long periods of time withoutmaterial distortion, and each mat or rubber article produced will beexactl like all of the others produced in that mol I claim:

1. A mold for rubber sheets and mats comprising a plate having base andtop portions composed of yielding material, and an embedded foraminousportion composed of a material which will not expand or distortlaterally' under vertical pressures.

2. A mold for rubber sheets and mats comprising base and top portions ofyielding material, and an embedded net of crossed wires rigidlyconnected with each other at the joints.

3. A mold for rubber sheets and mats comprising a sheet of rubber havinga foraminous metal backing, and having its opposite surface red.

4. A mold for'rubber articles comprising a vulcanized sheet of rubberhaving one surface figured, and the other surface provided with aforaminous metal backing.

5. A mold for rubber articles comprising a vulcanized sheet of rubberhaving one surface figured, and the other surface provided with aforaminous metal backing, said metal back being anchored to the rubbersheet by portions of rubber engaged in the openings of the metalelement.

LEROY M. BICKETT.

